Employer-sponsored 401(k) plans are sometimes touted as a way to put workers in charge of their own retirement funds. But increasingly, workers are automatically enrolled into plans, and their dollars are directed into target-date funds, which contain a mix of investments that are selected for them. Plan administrators say the shift to automatic savings comes, in part, because of new information about investor behavior. "Our view in 1980 was unsophisticated about individual decision-makers," says Stephen Utkus, director of the Vanguard Center for Retirement Research.